- Use high-level vague marketing speech like "helped reduce customers acquisition cost by $X" - The world is complex, who knows what that means in practice.
- List MOOCs, certificates, or free online courses on your resume. 99% of these require no commitment and don't teach you anything. Listing them signals that you care about cheap credentials more than learning. If you wanted to learn, you would've created a project out of it, tried to implement something, or written a blog post, etc. I'd rather see "I privately read books about X in my free time" than cheap MOOC credential signaling. That'd be more impressive and I could ask about it in an interview.
- List software like Excel or Google spreadsheets. I mean, if you're an engineer I'm assuming you can use a computer. Listing this means that you're living in a different world.
- List fluffy soft skills like "I am a good communicator" without any backup. Results speak louder than words.
- Too many spelling mistakes.
These are the things off the top of my head, I may add to it later.